Connection device for an internal heat exchanger

ABSTRACT

The invention relates to a connection device for an internal heat exchanger ( 14 ) having a connection block ( 21 ) comprising a first and a second through hole ( 24, 25 ), wherein an inlet opening ( 26 ) of the first through hole ( 24 ) can be connected on the high pressure side to a connection of the internal heat exchanger ( 14 ), and an outlet opening ( 27 ) of the first through hole ( 24 ) to an inlet of an evaporator ( 16 ), and an inlet opening ( 28 ) of the second through hole ( 25 ) can be connected to an outlet of the evaporator ( 16 ) and an outlet opening ( 28 ) of the second through hole ( 25 ) on the low pressure side to a connection of the internal heat exchanger ( 14 ), wherein a narrowing of the cross section ( 31 ) of the first through hole ( 24 ) is formed in the connection block ( 22 ) between the inlet opening ( 26 ) and outlet opening ( 27 ) and acts as a throttle point.

The invention relates to a connecting device for an internal heat exchanger as provided in a refrigeration circuit.

In US 2006/0,117,793 A, a refrigeration circuit to be used in an air conditioning system of a vehicle is disclosed. The condensed refrigerant is supplied to an expansion valve via an internal heat exchanger and a conduit attached thereto. The refrigerant, which is under high pressure, is expanded by the expansion valve and then flows to the evaporator with low pressure. The evaporator, in turn, is connected to the internal heat exchanger via a separate conduit. On the output side of the internal heat exchanger, a connector is provided which leads to the compressor. An assembly of this type suffers from the disadvantage of requiring a plurality of bolted connections to be provided for securing the expansion valve between the internal heat exchanger and the evaporator. In addition, due to the great number of connection points, the probability of leakage issues is enhanced and the assembly tends to be complex in terms of installation space requirements. Fabrication and assembly are costly and time-consuming.

The invention is therefore based on the object of providing a connecting device for an internal heat exchanger which reduces the number of connections and allows a compact, space-saving arrangement.

This objective is achieved, according to the present invention, by means of a connecting device having the characteristics of claim 1. The connecting device of the present invention provides a cross-sectional constriction formed in the connecting block between the inlet opening and the outlet opening of the first through bore, said cross-sectional constriction being realised in the form of a throttle point. This arrangement makes it possible to dispense with two additional connection points for the integration of a throttle point between the internal heat exchanger and the evaporator.

Furthermore, a compact, space-saving arrangement may be provided since the throttle point is incorporated into the connecting block of the connecting device. In particular, the fact that the throttle point is directly formed in the connecting block by means of a cross-sectional constriction of the first through bore ensures a simple and cost-effective fabrication. No additional components are needed for the configuration of the throttle point, since said throttle point is incorporated directly into the connecting block in the form of a cross-sectional constriction.

In a preferred configuration of the connecting device, provision is made for the cross-sectional constriction realised as a throttle point to have a cross-sectional area which is smaller than the cross-sectional area of the outlet opening in the first through bore. This is a simple manner of providing a throttle point which is defined by the geometric relationships between the cross-sectional area of the outlet opening and the cross-sectional area of the constriction in the through bore.

According to a preferred configuration of the invention, provision is made for the cross-sectional constriction to be channel-shaped or nozzle-shaped and to be preferably smaller by a multiple than the mean cross-section of the first through bore between the inlet opening and the outlet opening. Thus it is possible to provide, in a structurally simple manner, a throttle point for the connecting block, which is preferably made of a solid material in which the first and second through bores are realised by drilling/milling or the like. The cross-sectional constriction may also be realised in a stepped manner. The throttle point is preferably realised as a fixed throttle, which is to say that the connecting device having first and second through bores comprises a fixed throttle formed in the first through bore so as to expand a high pressure refrigerant at the throttle point and to have it flow to the evaporator with low pressure.

According to an advantageous configuration of the invention, provision is made for a mass flux flowing through the cross-sectional constriction to be capable of being regulated by a valve closure member of an expansion valve insertable into the through bore. This arrangement has the advantage that the connecting device may be equipped with an expansion valve without the necessity of providing additional interfaces for accommodating connectors between the expansion valve and tubes coming from the internal heat exchanger and leading to the evaporator.

The expansion valve insertable into the connecting block of the connecting device is preferably realised as a pressure differential valve. The working range of said pressure differential valve is determined by the pressure difference between the entrance side and the exit side of the through bore, which is to say by the high pressure prevailing at the inlet opening of the first through bore and by the low pressure present at the outlet opening of the first through bore.

The expansion valve insertable into the connecting block is preferably provided with a guiding element accommodating the valve closure member, a restoring device, and an adjusting device. The integrated arrangement thereof makes it possible for an expansion valve of this type to be realised using a very small number of components. These components may, for example, be insertable into the through bore individually, one after the other, preferably via the outlet opening of the first through bore.

The insertable expansion valve preferably has a guiding element realised as a sleeve in the form of a perforated disc or a sleeve having key-shaped tongues. The configuration as a sleeve in the form of a perforated disc has the advantage of providing a simple geometric structure, with a valve closure member being arranged in the centre, for example, and being surrounded by one or several through bores. An outer cylindrical surface of the guiding element abuts on a wall of the first through bore and may coaxially slide therein. The alternative configuration of the sleeve having key-shaped tongues is fabricated in a different manner and constitutes a bent sheet-metal part. The key-shaped tongues are equally applied to the wall portion of the through bore so that the guiding element is arranged in a coaxially slidable manner.

Furthermore provision is made for the insertable expansion valve to have the guiding element and the valve closure member firmly attached to each other or integrally formed as one single piece. Thus, the valve closure member may be securely lifted and guided by the guiding element. Depending on a given structural design, the embodiment as one single piece may also be selected as an embodiment in which the valve closure member and the guiding element are, for example, firmly connected to each other by means of a welded joint or a clamping connection.

The insertable expansion valve preferably has an adjusting device comprising at least one adjusting nut. This adjusting nut is in engagement with a threaded portion formed in the first through bore and arranged preferably downstream of the cross-sectional constriction. This makes it possible to adjust a preload force of the restoring device, which, in turn, permits to determine the opening instant of the expansion valve. Preferably, the adjusting device is provided with a holder for accommodating or supporting the restoring device in order to enable a centred reception thereof. This holder may also be integrally formed with the adjusting nut or firmly attached thereto.

The adjusting nut of the insertable expansion valve is provided at least with recesses in the shape of arcuate segments formed on the outer circumference or with through bores or with both of these. This, on the one hand, ensures optimal throughflow of the mass flux and, on the other, enables easy and rapid fastening of the expansion valve within the through bore.

According to a further preferred configuration of the invention, provision is made for the inlet opening of the first through bore and the outlet opening of the second through bore to be provided within one shared connecting bore formed in the connecting block, said connecting bore being situated adjacent to one side wall of the connecting block and being preferably realised as a blind bore. A further reduction of the number of connecting points that are to be sealed with respect to the outside environment can thus be achieved. In this embodiment, only the outlet opening of the first through bore, the inlet opening of the second through bore, and the connection point of the connecting bore are to be sealed relative to the outer environment, such that the number of connecting points requiring to be sealed off is reduced to three.

According to a further preferred embodiment of the connecting block, the connecting bore is realised as a stepped bore and serves for connecting a double-tube internal heat exchanger. Due to this stepped bore, an inner tube of the double-tube heat exchanger may be associated with a first step and the outer tube of the internal heat exchanger may be associated with a second step of the stepped connecting bore, which makes it possible to have a structurally simple separation between the high-pressure refrigerant to be supplied and the low-pressure refrigerant to be discharged.

Furthermore, provision is preferably made, when drilling a connecting bore into the connecting block, for the longitudinal axis of the cross-sectional constriction to be radially oriented with respect to the connecting bore and to merge with said connecting bore. This again allows to create structurally simple conditions. In the upstream direction, the cross-sectional constriction merges with an annular channel which is preferably formed after the connecting bore of the double-tube internal heat exchanger has been inserted into the stepped connecting bore. This annular channel forms the inlet opening of the first through bore, once the double-tube internal heat exchanger has been inserted.

The outlet bore arranged in the connecting block is preferably disposed coaxially with respect to the outlet opening of the second through bore. Thus it is possible to create an arrangement having a reduced flow resistance.

In addition, provision is preferably made for a double-tube internal heat exchanger to be insertable into the connecting bore and for at least one screen element to be disposed therebetween. In this way, the cross-sectional constriction may be protected against contaminants and, consequently, against any impairment of the expansion effect.

The screen element insertable into the connecting bore of the connecting block is preferably tubular or frusto-conical in shape and has annular sealing members formed preferably at least on the respective end faces. The one sealing member is operable to seal the environment with respect to the high-pressure side and the other sealing member is operable to seal the high-pressure side with respect to the low-pressure side. The screen element may thus serve at the same time for accommodating the sealing members and ensuring the respective sealing functions.

Furthermore, provision is preferably made for a connector of the double-tube internal heat exchanger to be connectable in a hermetically tight manner with the connecting block. In doing so, provision is particularly made to ensure that after the attachment of the connecting point said connecting point is secured by soldering or welding.

The invention, as well as other advantageous embodiments and developments thereof, will be described and explained in the following with reference being made to the examples shown in the drawings. The characteristics issuing from the description and the drawings may be applied according to the present invention either individually or as a plurality of features taken in any combination. In the drawings:

FIG. 1 is a schematic representation of a refrigeration circuit,

FIG. 2 is a perspective view of a first embodiment of a connecting device,

FIG. 3 is a schematic sectional view of an alternative embodiment of the connecting device, differing from FIG. 2,

FIG. 4 a is a schematic, detailed view of an expansion valve within the connecting device,

FIG. 4 b is a schematic, detailed view of an adjusting device of the expansion valve according to FIG. 4 a,

FIG. 5 is a schematic, detailed view of an alternative embodiment of an expansion valve within the connecting device, and

FIG. 6 is a schematic, detailed view of a connecting device according to FIG. 3, providing an alternative connection of an internal heat exchanger.

FIG. 1 shows a conventional layout of a refrigeration and/or thermal circuit 11 of, in particular, an air conditioning system to be used preferably in motor vehicles. A compressor 12 compresses a refrigerant, in particular R134a. The compressed refrigerant is supplied to a condenser 13 where heat exchange between the compressed refrigerant and the environment takes place in order to cool the refrigerant. Downstream of the condenser 13, an accumulator 17 or receiver may be provided in order to separate refrigerant in the gaseous phase from refrigerant in the liquid phase and at the same time to collect liquid refrigerant. The refrigerant discharged from the condenser 13 or from the accumulator 17 passes to an internal heat exchanger 14. Between the internal heat exchanger 14 and the evaporator 16, an expansion valve 15 is provided. The expansion valve 15 regulates the mass flux of the refrigeration and/or thermal circuit 11 depending on the prevailing pressure differential. The high-pressure refrigerant is expanded by the expansion valve 15 and, on the low-pressure side, continues its flow path towards the evaporator 16. In the evaporator 16, the refrigerant absorbs heat from the environment. The refrigerant then passes the internal heat exchanger and is again supplied to the compressor 12.

In use, the configurations of a connecting device 21 according to the present invention as described hereinafter in conjunction with the other figures differ as to the representation of the refrigeration circuit 11 in that the expansion valve 15 is not disposed separately in a conduit section between the internal heat exchanger 14 and the evaporator 16 but is incorporated within the internal heat exchanger 14.

FIG. 2 is a perspective representation of a first embodiment of the connecting device 21. This connecting device 21 comprises a connecting block 22 which is preferably realised in a solid manner or made of full material. A first through bore 24 and a second through bore 25 are formed in this connecting block 22. The first through bore 24 comprises an inlet opening 26 which is connectable, on the high-pressure side, to a connector of an internal heat exchanger 14. At the exit of the first through bore 24, an outlet opening 27 is provided which is connectable with a tubing not represented in greater detail or is directly connectable with the evaporator 16. The second through bore 25 has an inlet opening 28 arranged in parallel with the outlet opening 27, so that refrigerant arriving from the evaporator 16 may be introduced into the connecting block 22 or rather into the through bore 25. At the end of the second through bore 25, an outlet opening 29 is provided via which the refrigerant is passed to the internal heat exchanger 14.

According to a first embodiment not shown here, the through holes 24 and 25 may be realised in the form of straight bores extending throughout the connecting block 22. Alternatively, an angled arrangement may be provided, as represented for example in FIG. 2. It is not of essential importance that the inlet opening 26 of the first through bore 24 be formed on the same lateral wall as the outlet opening 29 of the second through bore 25. The same is true of the outlet opening 27 of the first through bore and the inlet opening 28 of the second through bore 25. These may also be arranged offset relative to each other, depending on a specific application.

According to the embodiment of FIG. 2, provision is made for the first through bore 24 to have two bore sections which are arranged at a right angle relative to each other. In the corner portion of the bore sections intersecting each other, a cross-sectional constriction 31 is formed which acts as a throttle point. Said cross-sectional constriction 31 is formed directly in the connecting block 22. Thus, the throttle point is integrally formed with the connecting block 22. This arrangement makes it possible, therefore, to provide a connecting device 21 for an internal heat exchanger 14 which has a regulating element that is incorporated in the connecting block 22. Thus, a compact, space-saving solution is provided which, in addition, may be fabricated in an easy manner.

FIG. 3 represents an alternative embodiment of a connecting device, differing from FIG. 2. In this embodiment, the inlet opening 26 of the first through bore 24 and the outlet opening 29 of the second through bore 25 differ from FIG. 2 in that they are provided within one shared connecting bore 33. Preferably, a stepped connecting bore 33 is provided. The transition region 34 is jointly formed by a bore section 35 and the outlet opening 29 of the second through bore 25, with the bore section 35 being preferably larger than the outlet opening 29. The cross-sectional constriction 31 is radially oriented with respect to the bore section 35 and arranged with a spacing from the outlet opening 29. Said cross-sectional constriction preferably merges with the bore section 35.

This connecting bore 33 is adapted for accommodating the double-tube internal heat exchanger 14. The interior heat exchanger 14 has an outer tube 36 the outer diameter of which is applied to the bore section 35 of the connecting bore 33 and extends at least partially into the connecting bore 33. On the outer tube 36, an annular collar 37 or flange or sleeve-like fastener is preferably provided which is applied to an end face 38 of the connecting block 22 and positions and fastens the internal heat exchanger 14 with respect to the connecting block 22. This annular collar 37 may serve the purpose of creating a hermetical seal by means of a welded or soldered connection, or else by means of a gasket, such as an O-ring seal or the like.

The outer tube 36 of the internal heat exchanger 14 extends to the cross-sectional constriction 31, or to its vicinity, but does not overlay it. An inner tube 39 of the internal heat exchanger 14 protrudes with respect to the outer tube 36 and is preferably applied to an end face 40 formed in the transition region 34 between the outlet opening 29 and the bore section 35. An arrangement of this type makes it possible for the inlet opening 26 of the first through bore 24 to be constituted by an annular channel between the inner tube 39 and the bore section 35 of the connecting bore 33.

This arrangement has the advantage that only one sealing point or connecting point with respect to the internal heat exchanger 14 is provided, such that in this connecting device 21 the number of connectors is reduced by one connecting point as compared to the connecting device of FIG. 2.

The connecting device 21 has, for example, an expansion valve 45, which is arranged downstream of the cross-sectional constriction 31, considering the flow direction of the refrigerant. This expansion valve 45 regulates the mass flux depending on the prevailing pressure conditions between the high-pressure side and the low-pressure side. A first embodiment of the expansion valve 45 is represented in an enlarged view in FIG. 4 a and a partial view thereof is represented in FIG. 4 b. FIG. 5 is an alternative configuration of an expansion valve 45, equally represented in an enlarged view.

The expansion valve 45 according to FIGS. 4 a and 4 b is provided as what is called a built-in expansion valve, which may be formed by a very small number of components.

A valve closure member 47 is applied to a valve seat 46 of the cross-sectional constriction 31 or of a connecting space. This valve closure member 47, which may, for example, be conical, is positioned with respect to the valve seat 46 by means of a guiding element 48 and is guided during opening and closing movements within the first through bore 24 by said guiding element 48 in such a manner as to be axially slidable within said through bore 24. The guiding element 48 is preferably realised as a sleeve 58 in the form of a perforated disc and accommodates the valve closure member 47 in its centre. An outer cylindrical surface of the sleeve 58 is applied to a wall portion of the first through bore 24, such that the valve closure member 47 is guided therein in an axially slidable manner. Between the guiding element 48 and an adjusting device 49, a restoring device 51, preferably in the form of a compression spring, is provided and positions the valve closure member 47 to a closing position, which may be considered its neutral position or initial position.

The adjusting device 49 comprises at least one adjusting nut 50 which is provided on its outer circumference with recesses 52, in particular recesses 52 in the shape of arcuate segments, as represented for example in FIG. 4 b. In addition, a central bore 53 may be provided. Thus, a sufficiently wide cross-section may be provided for the refrigerant to flow through. This bore 53 may further be used in order to position the adjusting nut 50 on a threaded portion 54 provided in the through bore 24. In this embodiment the restoring device 51 is applied to a holder 56 which is positioned centrally with respect to the adjusting nut 50. This separate arrangement has the advantage that when setting the preload of the restoring device 51, which defines the opening instant of the valve closure member 47 in accordance with the pressure differential, no torque is transmitted from the adjusting nut 50 to the restoring device 51, as the two elements are rotationally decoupled from each other via the holder 56. Depending on the materials used and/or the requirements envisaged, the holder 56 may also be integrally formed with the adjusting nut 50.

The bore 53 inside the adjusting nut 50 may, in addition, be realised as a tool holder for mounting the adjusting device 49. In the embodiment represented in FIG. 4 the expansion valve 45 may, for example, consist of only four components. These are formed by the adjusting nut 50, the holder 56, the restoring device 51, and the valve closure member 47 arranged on the guiding element 48. The guiding element 48 and the valve closure member 47 may be integrally formed or may consist of two pieces which are subsequently firmly interconnected.

In FIG. 5, an alternative embodiment of the expansion valve 45, differing from FIG. 4, is represented. This embodiment differs in respect to the configuration of the valve closure member 47 and the guiding element 48. As to the rest, the components are preferably identical in construction. The valve closure member 47, instead of having a conically shaped tip, is realised as a ball that is attached to a sleeve 58 having key-shaped tongues 59 or legs. These key-shaped tongues 59 are applied to the wall of the first through bore 24, such that an axial, slidable arrangement of the valve closure member 47 relative to the cross-sectional constriction 31 is enabled.

FIG. 6 represents an alternative configuration of a connecting device 21 having an internal heat exchanger 14 connectable thereto. This embodiment differs with respect to the one shown in FIG. 3 only in so far as a screen element 61 is arranged between the ends of the outer and inner tubes (36, 39) disposed within the connecting bore 33. This screen element 61 may, for example, be conically shaped and be provided with sealing members 62, i.e. annular sealing members 62, arranged on the respective front ends. These are operable, on the one hand, to place the screen element 61 in the correct position and, on the other hand, to form a tight seal between the outer tube 36 and the bore portion 35 of the connecting bore 33 as well as between the inlet opening 26 of the first through bore 24 and the outlet opening 29 of the second through bore 25. This sealing member 62 may be applied frontally to the end face 40, in accordance with the embodiment of the connecting device 21 shown in FIG. 3, or may be applied to a further step of the connecting bore 33, as represented in FIG. 6.

The configuration of the connecting bore 33 is not affected by the question of whether or not an expansion valve 45 is inserted into the connecting device 31.

The diameter of the cross-sectional constriction 31 as well as the length and/or the geometry thereof may be adapted depending on the degree of refrigerant expansion required by a given application to occur at this throttle point. The cross-sectional constriction 31 of the through bore 24 is realised as a connecting channel or connecting passageway. 

1. A connecting device for an internal heat exchanger provided with a connecting block having first and second through bores, wherein an inlet opening of the first through bore is connectable on the high-pressure side to a connector of the internal heat exchanger and an outlet opening of the first through bore is connectable with an entrance of an evaporator, and wherein an inlet opening of the second through bore is connectable with an outlet of the evaporator and an outlet opening of the second through bore is connectable on the low-pressure side with a connector of the internal heat exchanger, wherein between the inlet opening and the outlet opening a cross-sectional constriction of the first through bore is formed within the connecting block and is operable as a throttle point.
 2. The connecting device as claimed in claim 1, wherein the cross-sectional constriction realised in the form of a throttle point has a cross-sectional area which is smaller than the cross-sectional area of the outlet opening in the first through bore.
 3. The connecting device as claimed in claim 1, wherein the cross-sectional constriction is channel-shaped or nozzle-shaped or stepped.
 4. The connecting device as claimed in claim 1, wherein a mass flux flowing through the cross-sectional constriction is controllable by means of a valve closure member of an expansion valve insertable into the first through bore.
 5. The connecting device as claimed in claim 4, wherein the expansion valve is controllable by a pressure differential between a high-pressure side upstream of the cross-sectional constriction and a low-pressure side downstream of the cross-sectional constriction, as considered with respect to the flow direction of the refrigerant.
 6. The connecting device as claimed in claim 4, wherein the expansion valve insertable into the connecting block is provided with a guiding element accommodating the valve closure member, a restoring device and an adjusting device.
 7. The connecting device as claimed in claim 6, wherein the guiding element is realised as a sleeve in the form of a perforated disc or as a sleeve having key-shaped tongues.
 8. The connecting device as claimed in claim 6, wherein the guiding element and the valve closure member are firmly connected to each other or are integrally formed as a single piece.
 9. The connecting device as claimed in claim 6, wherein the adjusting device comprises an adjusting nut.
 10. The connecting device as claimed in claim 9, wherein the adjusting nut is provided with recesses which are realised at least as recesses in the shape of arcuate segments formed on the outside circumference, or as through holes.
 11. The connecting device as claimed in claim 1, wherein the inlet opening of the first through bore and the outlet opening of the second through bore are formed within a shared connecting bore.
 12. The connecting device as claimed in claim 11, wherein the connecting bore is realised as a stepped bore and serves for connecting a double-tube internal heat exchanger.
 13. The connecting device as claimed in claim 11, wherein the longitudinal axis of the cross-sectional constriction is oriented radially with respect to the connecting bore and merges with the connecting bore.
 14. The connecting device as claimed in claim 11, wherein the outlet opening of the second through bore is arranged coaxially with the connecting bore.
 15. The connecting device as claimed in claim 11, wherein between a frontal end of an outer tube of the internal heat exchanger and an inner tube protruding therefrom, at least one screen element is provided and said screen element extends all over the inlet opening of the first through bore.
 16. The connecting device as claimed in claim 15, wherein the screen element is tubular or frusto-conical in shape and has at least two sealing members such that one of said sealing members forms a tight seal between the outer tube of the internal heat exchanger and a bore section of the connecting bore and the other sealing member forms a tight seal of the inner tube and outer tube of the internal heat exchanger with respect to the connecting bore.
 17. The connecting device as claimed in claim 1, wherein the internal heat exchanger is connectable in a hermetically tight manner with respect to the connecting block.
 18. The connecting device as claimed in claim 9, wherein the adjusting device comprises a holder capable of being arranged on the adjusting nut and operable to accommodate the restoring device.
 19. The connecting device as claimed in claim 11, wherein the connecting bore is realized as a blind bore formed in a side wall of the connecting block. 